This invention relates to an arcuate wall as part of a revolving door, and more particularly to arcuate sidewall members made at least partly of glass.
In order to make the entrances to buildings such as airports, hospitals, shops, administrative buildings, etc. look more attractive, it is desirable to have door leaves and the surrounding structure made from glass or with glass as a substantial part. An unimpeded or only slightly impeded look through the door construction improves traffic flow through the door by reducing the number of incidents where persons bump into one another due to lack of visibility.
The arcuate side walls in revolving doors are usually made of panels of non-transparent material such as stainless steel, or with annealed glass bent to a right cylindrical shape. A transparent plastic with sufficient scratch hardness to withstand the effect of the constantly passing sealing element (felt or brush) on the edges of each rotating door leaf is not presently available.
The use of bent, annealed glass in a door construction results in a number of disadvantages and problems.
The costs of manufacturing are high for bent glass in dimensions to be used and manufactured in the relatively small number of pieces in question with the accuracy required. The high cost of the mold for bending further tends to limit the number of door diameters available, thus limiting the architectural freedom in designing an entrance.
A problem associated with the use of annealed glass is its tendency to break into large fragments with dangerously sharp edges. For security reasons and because of the improved strength thereof, tempered or laminated the bent glass in question has led to reluctant acceptance of the use of annealed glass, and the attendant risk of personal injury in the event of breakage. This risk may be reduced somewhat by use of an increased thickness of the glass.
Another disadvantage of using bent annealed glass is the difficult transportation and mounting of these heavy and voluminous (because of the arcuate shape) pieces of glass. The handling of the panes entails a high breakage risk, adding substantially to the final price of the product.
Earlier attempts to make use of flat pieces of glass in the curved walls in revolving doors in order to make the use of tempered and laminated glass economically feasible have failed, either because the suggested design did not permit smooth rotation of the door; the sealing between the edges of the door leaves and the arcuate wall could not be maintained throughout the passage; or because the view through the transparent area was too narrow to be attractive and/or to have any effect in improving the traffic flow through the door.
It is an object of the present invention to overcome economic and technical disadvantages and problems related to earlier designs of transparent panels for arcuate walls forming part of revolving doors.